Electric fuse.



T. E. MURRAY, JR. ELECTRIC FUSE.

APPLIGATION FILED MAR.2B. 1914A 1, l 20,226. Patented Dec. s, 1914.

UNTTED sTaTEs PATENT oEEroE.

- ".'LIHOIIYILAS EDWARD MURRAY, J' R., 0F BROOKLYN, NEW YORK, ASSIGNOR TO THOMAS E.

MURRA.Y,' OF NEW'YORK, N. Y.

ELECTRIC FUSE. i

To all whom., it may concern Be it known that I, THOMAS E. MURRAY,

- J r., a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York,have invented a certain new and useful -Improvement in Electric Fuses, of which-the following is a specifica-- tion. l

The invention relates to electric fuses. It is based on the discovery of and embodies a new principle, namely, that if in a fuse strip a blowing point be localized, and the said blowing point be inclosed in a solid body of insulating material, which forms Vwith said strip a gas-tightA joint on both sides of saidblowing point, then the destruction of the strip upon explosion will extend no farther than said joints, or, in otherwords, will be confined within said insulating body, and the gas generated in the confined space within said body will blow the ruptured ends of said strip out of said space, as from a gun, thus widely separating said ends and even curling or bending them back on themselves.

In the accompanying drawings-Figure l is a longitudinal section of my fuse. Fig. 2 is a transverse section on line of Fig. l. Fig. 3 shows a fuse strip separately. Fig. Ll is an enlarged cross section of the middle portion of the partition of insulating material, showing the localized blowing point of the strip in the slot of said partition. Fig. 5 is a face view of the same portion of the partition, showing said strip in cross section. Figs. (3 and 7 are sectional views similar to Fig. l. Fig. 6 shows the fuse at the instant of blowing, and exhibits the ruptured portion of the `fuse strip as confined .in the slot in the partition] the view being taken at right angles to Fig. l. Fig. 7

. shows the fuse strip after the ruptured ends have been expelled from the partition slot by the gas formed therein, and exhibits the' throwing back and curling up of the parts of the fuse, as hereinafter described.

Similar letters of reference indicate like parts.

My invention may be embodied in many diderent constructions. I herein illustrate its application to the simple and well known cartridge fuse, which comprises a cylindrical shell A of liber or other suitable insulating material, metal caps B on the ends of said cylinder, a fuse strip C within the shell Specification of Letters Patent.

Patented Dec. 8, 1914.

pplieation filed March 28, 1914. Serial No. 827,862.

and connected at its ends to said caps, and sometimes asbestos lining disks D vcovering the inner faces of thel caps.

I provide within the shell and closely fitting the same, a partition disk E of insulating material. In that disk I make a slot F. I make the fuse strip C preferably in the form of a flat band. I localize the blowing point at H in that strip by reducing its cross sectional area at said point by means of indentations or recesses in opposite edges of the strip. The localized blowing point H is to lie in the slot F, and the insulating body E is to form a gas-tight joint with the strip on both sides of and in proximity to said blowing point. Where the blowing point is formed, as here shown, by a'contraction in the strip, the insulating body E is to form a gas-tight joint with the strip on both sides of said contraction. In other words, the strip is to completely close or plug both ends of the slot, as indicated' at J, Fig. 4, and

the localized blowing point, however produced, is to lie in that part of the strip which is within the slot and between said closed or plugged ends. To this end in the embodiment here shown, the width a, Fig. 4, of the recesses in the edge of the strip is made less than the thickness of body E. `When these conditions are fulfilled, I iind by actual and repeated tests that the following results ensue: The portion of the strip which is destroyed is limited to so much of the strip as lies in the partition slot, as indicated'in Fig. 5, so that the destruction or rupture does not extend to the parts of the strip voutside of said partition. (2) By reason of the' confinement of the gases of` explosion to the partition slot, said gases act to throw the ruptured ends of the strip immediately out of the slot, and to force them asunder, so that the gap between them then becomes so great that there can be no passage of current between them, and this passage is still further prevented by the barrier due to the presence of the insulating partition. In practice, I have repeatedly observed that the ends of the strip are not only widely separated, but curled or bent back on themselves, as shown in Fig. 7.

IFhe advantages will be obvious to all skilled in the art, since the conditions of practically a perfect fuse are here realized. No filling of plaster or the like within the fuse case is either necessary or desirable- The whole explosion is limited to the very small confined space afforded by the partition slot, and the correspondingly small amount of gas generated does not rupture the shell. The strip beyond the partition not being consumed, the eects of explosion do not extend to the end caps and terminal connections.

I do not limit myself to the particular way of producing a localized blowing point in a strip of fusible material shown in Fig. 3, since there are many known ways. The body of insulating material may or may n'ot form a partition in the shell or form a barrier between the fuse terminals. The fuse strip may be lof cross section other than polygonal.

I claim:

1. An electric fuse, comprising a fuse strip having a localized blowing point, and a body of solid insulatin material inclosing said blowing point and orming a gas-tight joint with said strip on both sides of and in proximity to said blowing point; the width ofsaid joint being such that upon the rupture of the fuse at said localized blowing point, the separated 'unmelted parts of said fuse immediately adjacent to said point of rupture shall be expelled from said body.

ately adjacent to said point of rupture shall be expelled from said body.

3. An electric fuse, comprising a shellfa' fuse strip therein having a localized blowing point, a partition of solid insulating material in said shell inclosing said blowing point and forming a gas-tight joint with said strip on both sides of and in proximity to said blowing point; the width of said joint beingsuch that upon the rupture of the fuse' at said localized blowing point, the separated unmelted parts of said fuse immediately adjacent to said point of rupture shall be expelled from said partition.

In testimony whereof I have aixed my signature in presence of two witnesses.

l I THOMAS EDWARD MURRAY, JB.

Witnesses:

GERTRUDE T. PORTER, MAY T. MCGARRY. 

